Gas cell, gas cell manufacturing apparatus, and gas cell manufacturing method

ABSTRACT

A manufacturer of gas cells performs an arrangement process of arranging solid substances at positions corresponding to holes each of which is provided on each of a plurality of cells. Then, the manufacturer of the gas cells performs an accommodation process of accommodating gas in inner spaces of the cells through an air flow path connected to the holes. Further, the manufacturer of the gas cells performs a sealing process of sealing the spaces by melting the solid substances to close the holes corresponding to the solid substances.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional patent application of U.S. application Ser. No.13/417,647 filed Mar. 12, 2012 which claims priority to Japanese PatentApplication No. 2011-064217 filed Mar. 23, 2011 all of which areincorporated by reference herein in their entireties.

BACKGROUND

1. Technical Field

The present invention relates to techniques of a gas cell, a gas cellmanufacturing apparatus and a gas cell manufacturing method.

2. Related Art

A magnetic sensor using optical pumping is used for a magnetic resonanceimaging (MRI) apparatus or the like. The magnetic sensor has a cellwhich encapsulates alkali metal atoms or the like in a gaseous state. Ifpump light having a circularly polarized component is irradiated ontothe cell, the encapsulated atoms are excited. Further, if probe lighthaving a linearly polarized light component is irradiated onto the cellsuch that the probe light intersects with the pump light, the excitedatoms rotate a polarization plane of the linearly polarized lightcontained in the probe light in accordance with a magnetic field appliedfrom the outside. The magnetic sensor detects a rotation angle of thepolarization plane of the probe light transmitted through the cell so asto measure the magnetic field.

Since the cell is transmissive to light, at least a part of the cellneeds to be formed by a transparent member. Further, the cell isrequired to be sealed for accommodating the excited atoms. As atechnique of making an inner portion of a container formed by atransparent member into a sealed state, for example, the followingmethod of manufacturing an image display apparatus has been disclosed inJP-A-10-64414. The method of manufacturing an image display apparatus asdisclosed in JP-A-10-64414 is a method including softening a part of aglass-made exhaust pipe attached to an envelope with an electric heatingunit (first process), extending the exhaust pipe in a shaft direction ofthe exhaust pipe so as to make an outer diameter thereof smaller (secondprocess), heating the portion of which outer diameter has been madesmaller to a temperature of equal to or higher than that in the firstprocess again so as to melt and seal the portion (third process),cutting the molten portion (fourth process), and gradually cooling theportion with the electric heating unit (fifth process).

SUMMARY

An advantage of some aspects of the invention is to manufacture aplurality of gas cells each of which has a uniform volume andaccommodates gas having a uniform concentration in comparison with acase where a glass tube for exhausting gas is used.

A gas cell manufacturing method according to an aspect of the inventionincludes arranging solid substances at positions corresponding to holeseach of which is provided on each of a plurality of cells, accommodatinggas in inner spaces of the cells through an air flow path connected tothe holes, and sealing the spaces by melting the solid substances toclose the holes corresponding to the solid substances. With thisconfiguration, a plurality of gas cells each of which has a uniformvolume and accommodates gas having a uniform concentration can bemanufactured in comparison with a case where a glass tube for exhaustinggas is used.

In the gas cell manufacturing method according to the aspect of theinvention, it is preferable that the method further include generatingtemperature gradient on inner walls of the cells such that a temperatureis lower as is farther from the holes of the cells. With thisconfiguration, a material to be accommodated in the inner spaces of thecells can be reliably prevented from being not accommodated incomparison with a case where the temperature gradient is not generated.

Further, in the gas cell manufacturing method according to the aspect ofthe invention, it is preferable that the method further include formingthe air flow path with a recess by attaching a plate on which the recessis provided to the cells such that the holes are arranged along therecess, and removing the plate having the recess which forms the airflow path from the cells after the sealing. With this, configurations offinished gas cells can be made simple in comparison with a case wherethis configuration is not provided.

Further, in the gas cell manufacturing method according to the aspect ofthe invention, it is preferable that the method further includereinforcing the sealing of the spaces by bonding plate-form members tothe cells so as to cover the holes closed by the solid substances afterthe removing. With this configuration, the air flow path is removed sothat sealing of the solid substances exposed to the outside can bereinforced.

Further, in the gas cell manufacturing method according to the aspect ofthe invention, it is preferable that the method further includeseparating the cells from one another by cutting separation walls whichpartition inner spaces of the cells. With this configuration, aplurality of gas cells which are individually arranged for use can bemanufactured.

Further, in the gas cell manufacturing method according to the aspect ofthe invention, it is preferable that the method further includeassembling the plurality of cells by bonding a first plate, a secondplate which is arranged so as to be opposed to the first plate and onwhich holes penetrating through the second plate in the thicknessdirection are provided, and the separation walls which are arrangedbetween the first plate and the second plate to one another. With thisconfiguration, the gas cells can be manufactured by bonding the plates.

Further, in the gas cell manufacturing method according to the aspect ofthe invention, it is preferable that the assembling include installing ageneration source which generates the gas in at least one cell among thecells, and the accommodating include making the installed generationsource generate the gas. With this configuration, gas can be generatedin the spaces after the spaces in the plurality of cells are connectedto only the air flow path and are shielded from an external space.

Further, in the gas cell manufacturing method according to the aspect ofthe invention, it is preferable that two or more holes be provided forat least one cell among the plurality of cells. With this configuration,flow of gas in the spaces is made difficult to be stagnated.

Further, in the gas cell manufacturing method according to the aspect ofthe invention, it is preferable that the air flow path be reduced indiameter or closed such that the gas is difficult to flow through aportion on which the two or more holes provided for the one cell areconnected to one another in comparison with other portions. With thisconfiguration, gas to be flowed in the spaces can be suppressed fromflowing in the air flow path.

Further, in the gas cell manufacturing method according to the aspect ofthe invention, it is preferable that the gas contain atoms which rotatea polarization plane of linearly polarized light in accordance with amagnetic field if the atoms are excited with light. With thisconfiguration, a plurality of gas cells which are used for measuring amagnetic field and each of which has a uniform volume and accommodatesgas having a uniform concentration can be manufactured in comparisonwith a case where a glass tube for exhausting gas is used.

A gas cell manufacturing apparatus according to another aspect of theinvention includes an arrangement unit which arranges solid substancesat positions corresponding to holes each of which is provided on each ofa plurality of cells, an accommodation unit which accommodates gas ininner spaces of the cells through an air flow path connected to theholes, and a sealing unit which seals the spaces by melting the solidsubstances to close the holes corresponding to the solid substances.With this configuration, a plurality of gas cells each of which has auniform volume and accommodates gas having a uniform concentration canbe manufactured in comparison with a case where a glass tube forexhausting gas is used.

A gas cell according to still another aspect of the invention includes awall for separating a space which accommodates gas containing atomswhich rotate a polarization plane of linearly polarized light inaccordance with a magnetic field if the atoms are excited with lightfrom an outer space. In the gas cell, a hole provided on the wall isclosed by a molten solid substance.

Further, in the gas cell according to the aspect of the invention, it ispreferable that a plate-like member be bonded to the wall so as to coverthe hole from the outside.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a view illustrating an outer appearance of gas cells which aremanufactured by a manufacturing method according to an embodiment.

FIG. 2 is a flowchart illustrating main manufacturing processes of themanufacturing method according to the embodiment.

FIG. 3 is a view illustrating a state of the gas cells in a middle of anassembling process.

FIG. 4 is a view illustrating a state of the gas cells when theassembling process has been completed.

FIG. 5 is a schematic view illustrating a hole provided on a ceilingplate in an enlarged manner.

FIG. 6 is a view illustrating a state of the gas cells in an arrangementprocess.

FIG. 7 is a view illustrating an air flow path plate.

FIG. 8 is a view illustrating a state of the gas cells in an air flowpath formation process.

FIG. 9 is a view illustrating a state of the gas cells in anaccommodation process.

FIG. 10 is a view illustrating a state of the gas cells in a sealingprocess.

FIG. 11 is a view illustrating a state of the gas cells when the sealingprocess has been completed.

FIG. 12 is a view illustrating a state of the gas cells when an air flowpath removal process has been completed.

FIG. 13 is a view illustrating a state of the gas cells in a reinforcingprocess.

FIG. 14 is a view illustrating a state of the gas cells in a separationprocess.

FIG. 15 is a view illustrating a state of the gas cells when theseparation process has been completed.

FIG. 16 is a view illustrating a state of the gas cells in a coolingprocess according to a variation.

FIG. 17 is a view illustrating a state of the gas cells in anaccommodation process according to a variation.

FIG. 18 is a view illustrating a state of the gas cells in theaccommodation process according to a variation.

FIG. 19 is a view illustrating an example of a configuration of amanufacturing apparatus for manufacturing a gas cell according to avariation.

DESCRIPTION OF EXEMPLARY EMBODIMENTS 1. Embodiment

FIG. 1 is a view illustrating an outer appearance of gas cells 90 whichare manufactured by a manufacturing method according to an embodiment ofthe invention. A space in which the gas cells 90 are arranged isillustrated in a right-handed coordinate system for explaining shapesand arrangement of the gas cells 90. Further, a symbol that a whitecircle having a black circle therein among coordinate symbols asillustrated in the drawings subsequent to FIG. 3 below indicates anarrow pointing to the front side of a paper plane from the rear sidethereof. Further, a symbol that a white circle having two segmentstherein, which are intersected with each other, among the coordinatesymbols as illustrated in the drawings indicates an arrow pointing tothe rear side of a paper plane from the front side thereof. A directionin which an X component increases in the space is referred to as a +xdirection, a direction in which the x component decreases is referred toas a −x direction. As for y and z components, a +y direction, a −ydirection, a +z direction, and a −z direction are defined in the samemanner as the x component. It is to be noted that in the followingembodiment, the −z direction corresponds to the gravity direction.

FIG. 2 is a flowchart illustrating main manufacturing processes of themanufacturing method according to the embodiment of the invention. Themanufacturing method according to the embodiment of the inventionincludes an assembling process (step S101), an arrangement process (stepS102), an air flow path formation process (step S103), an accommodationprocess (step S104), a sealing process (step S105), an air flow pathremoval process (step S106), a reinforcing process (step S107), and aseparation process (step S108). The gas cells 90 as illustrated in FIG.1 are in a state after the reinforcing process has been completed andbefore the separation process is started. Five gas cells 90 asillustrated in FIG. 1 are arranged in the +y direction. Hereinafter, theprocesses as illustrated in FIG. 2 are described by usingcross-sectional views seen from a line III-III as illustrated in FIG. 1.

1-1. Assembling Process

FIG. 3 is a view illustrating a state of the gas cells in a middle ofthe assembling process. In the assembling process in the manufacturingmethod according to the embodiment of the invention, two side wallplates 21 and four separation wall plates 20 are bonded to a bottomplate 10 by fusion bonding. The bottom plate 10, the side wall plates21, and the separation wall plates 20 are plates each of which is formedby a transparent member such as a glass. Further, after the bottom plate10, the side wall plates 21, and the separation wall plates 20 have beenbonded to one another in the above manner, a front plate is bonded tothem from the +x direction and a rear plate is bonded to them from the−x direction by fusion bonding (the front plate and the rear plate arenot illustrated). Each of the front plate and the rear plate is a plateformed by a transparent member such as a glass. With this, a structurehaving a quadrangular prism shape, which has five openings, isassembled. The five openings open in the +z direction and are arrangedin line in the +y direction. As a bonding method of the members, abonding method with a glass having a low melting point or a brazingmaterial may be applied instead of the fusion bonding in which parts ofthe members are molten by heating so as to bond the members to oneanother as described above. Further, anodic bonding performed by heatingand voltage application, optical bonding by using a resin which is curedby irradiating the resin with light such as ultraviolet rays, or thelike may be applied. In addition, the members may be bonded to oneanother by employing optical contact in which bonding surfaces of themembers, which have been precisely ground, are made contact with oneanother while pressurizing the bonding surfaces of the members as thebonding method of the members.

In the assembling state as illustrated in FIG. 3, an ampule 30 is putinto a space 11 through one of the openings (opening at the most −ydirection side) so as to be installed in the space 11. The ampule 30 isformed by a material that is broken if any energy such as a mechanical,thermal, or optical impact is applied to an outer frame thereof. As theoptical impact, short-pulse laser is irradiated onto the outer frame,for example. Two or more materials are stored in the ampule 30 so as tobe separated from one another. The two or more materials generate alkalimetal vapor if the materials are mixed to each other. For example, achloride and a reducing agent are used for these materials. That is tosay, the process of installing the ampule 30 in the space 11 is anexample of an installation process of installing a generation sourcewhich generates the gas in at least one cell among the cells.

It is to be noted that a material that generates alkali metal vapor byapplying Joule heat to only the material or heating it with laserirradiation, such as alkali metal azide, may be encapsulated in theampule 30. In this case, the two or more materials are not required tobe stored in the ampule 30 and a material of single type may be storedtherein.

FIG. 4 is a view illustrating a state of the gas cells when theassembling process has been completed. In FIG. 3, the bottom plate 10,the side wall plates 21, the separation wall plates 20, the front plate,and the rear plate which have been assembled, have five openings whichopen in the +z direction. A ceiling plate 40 is attached to them so asto cover the openings. The ceiling plate 40 (second plate) is arrangedso as to be opposed to the bottom plate 10 (first plate) and isfusion-bonded to the front plate, the rear plate, the side wall plates21 and the separation wall plates 20. If these members are bonded to andcombined with one another, an inner portion of the structure ispartitioned into five spaces 11 a, 11 b, 11 c, 11 d, and lie(hereinafter, these spaces are collectively referred to as “spaces 11”when they need not be particularly distinguished from one another), asillustrated in FIG. 4.

Holes 41 are provided on the ceiling plate 40 at positions each of whichcorresponds to each space 11. FIG. 5 is a schematic view illustratingthe hole 41 (V portion in FIG. 4) provided on the ceiling plate in anenlarged manner. Each hole 41 includes a large-diameter portion 411 anda small-diameter portion 413. The large-diameter portion 411 is providedon the ceiling plate 40 at the +z direction side. The small-diameterportion 413 is provided on the ceiling plate 40 at the −z direction sideso as to be concentric to the large-diameter portion 411. The diameterof the large-diameter portion 411 is larger than the diameter of thesmall-diameter portion 413. A step 412 is formed due to the differencein size thereof. That is to say, the ceiling plate 40 is arranged so asto be opposed to the first plate and is an example of the second plateon which holes penetrating therethrough in the thickness direction areprovided. The assembling process is an example of an assembling processfor assembling the plurality of cells by bonding a first plate, a secondplate which is arranged so as to be opposed to the first plate and onwhich holes penetrating through the second plate in the thicknessdirection are provided, and the separation walls which are arrangedbetween the first plate and the second plate to one another.

Both of the large-diameter portion 411 and the small-diameter portion413 have substantially circular shapes when seen in the +z direction.However, the shapes thereof are not limited thereto and may be ovalshapes, rectangular shapes, and other various polygonal shapes. It is tobe noted that the holes 41 may be plated by tungsten (W), nickel (Ni),gold (Au), or the like.

1-2. Arrangement Process

FIG. 6 is a view illustrating a state of the gas cells in thearrangement process. Solid substances 50 are arranged at positions eachof which corresponds to each hole 41 provided on the ceiling plate 40for each space 11. Each solid substance 50 is formed by a gold-basedalloy solder including Au—Sn or Au—Ge and a shape thereof is a sphericalshape. Since a diameter of each solid substance 50 is longer than thediameter of each small-diameter portion 413, a part thereof is placed oneach step 412 such that the solid substance 50 does not drop into eachspace 11. Further, the solid substances 50 have shapes which do notcompletely close the small-diameter portions 413 in a state of beingplaced on the steps 412. Therefore, the spaces 11 and a space at the +zdirection side of the ceiling plate 40 are communicated with one anotherthrough the holes 41. That is to say, the large-diameter portions 411have a function of positioning the solid substances 50 at positionscorresponding to the holes 41 on an xy plane of FIG. 6. The steps 412have a function of preventing the solid substances 50 from dropping intothe spaces 11. Therefore, the solid substances 50 do not inhibit airfrom flowing through the holes 41. It is to be noted that the shape ofeach solid substance 50 is not limited to the spherical shape and may bea rectangular parallelepiped, a regular hexahedron, a regulartetrahedron, or the like. In other words, it is sufficient that thesolid substances 50 have shapes that do not close the small-diameterportions 413. Further, the material of each solid substance 50 is notlimited to the gold-based alloy solder and may be a glass having a lowmelting point, for example. In this case, the above-described plating onthe holes 41 may be not necessary.

1-3. Air Flow Path Formation Process

FIG. 7 is a view illustrating an air flow path plate 60 when seen towardthe +z direction. As illustrated in FIG. 7, a groove 61 extending in the+y direction is provided on a surface of the air flow path plate 60 atthe −z direction side. The groove 61 is an example of a recess and isrecessed in comparison with a surface of the air flow path plate 60 atthe −z direction side. FIG. 8 is a view illustrating a state of the gascells in the air flow path formation process. As illustrated in FIG. 8,the air flow path plate 60 is attached to the ceiling plate 40 from the+z direction side of the ceiling plate 40 by fusion bonding or the like.With this, an air flow path 62 connecting the holes 41 is formed withthe surface of the ceiling plate 40 at the +z direction side and thegroove 61 of the air flow path plate 60. The five spaces 11 communicatewith one another through the air flow path 62 and the holes 41 connectedto the air flow path 62. That is to say, the air flow path formationprocess is an example of a formation process of forming the air flowpath with a recess by attaching a plate on which the recess is providedto the cells such that the cells are arranged along the recess.

If the air flow path formation process has been completed, although thefive spaces 11 communicate with one another through the air flow path62, the five spaces 11 are shielded from external spaces at the +zdirection side of the air flow path plate 60 and at the −z directionside of the bottom plate 10. Accordingly, in order to make a time duringwhich spin polarized states of the alkali metal atoms are kept longer,inert gas such as helium (He), Argon (Ar), Neon (Ne), and Nitrogen (N₂)may be encapsulated into each space 11 before the five spaces 11 areshielded from the external spaces. Alternatively, paraffin, asilane-based material or the like may be coated on inner walls of theaccommodation spaces before the five spaces 11 are shielded fromexternal spaces. Further, the above-described recess is not limited to arecess extending in one direction like the groove 61. For example, whenthe spaces 11 arranged in the +y direction are further arranged in the+x direction in a matrix form and an air flow path plate is attachedthereto, the recess may be a recess drilled broadly and thinly insteadof the groove having the lengthwise direction. In other words, it issufficient that the recess makes it possible to form the air flow pathby attaching a plate having the recess to the cells such that the holesare arranged along the recess. Further, the recess may be provided noton the air flow path plate 60 but on the ceiling plate 40. In this case,it is sufficient that the recess is provided on the ceiling plate 40 atthe +z direction side and is attached to a flat surface of the air flowpath plate 60 so as to form an air flow path. An air flow path formed ina pipe form may be directly joined to the holes 41 instead of attachinga plate-form member like the air flow path plate 60 to the ceiling plate40.

1-4. Accommodation Process

FIG. 9 is a view illustrating a state of the gas cell in theaccommodation process. A manufacturer of the gas cells applies ashort-pulse laser beam 31 to the ampule 30 as the above-described energyso as to break an outer skin of the ampule 30. If the outer skin isbroken, the ampule 30 becomes a used broken ampule 32 and is left in thespace 11 a. Then, the materials stored in the ampule 30 are mixed witheach other so that chemical reaction occurs. With the chemical reaction,gaseous alkali metal atoms (alkali metal vapor) are generated and thespace 11 a is filled with the alkali metal vapor. That is to say, theprocess of breaking the outer skin of the ampule 30 so as to generatethe alkali metal vapor is an example of a generation process of makingthe installed generation source generate gas by applying energy from theoutside of the cell. The alkali metal vapor flows into the air flow path62 through the hole 41 and is diffused to other spaces 11 b, 11 c, 11 d,11 e through other holes 41. With this, the alkali metal vapor isaccommodated in each space 11.

1-5. Sealing Process

FIG. 10 is a view illustrating a state of the gas cells in the sealingprocess. After the alkali metal vapor is accommodated in each space 11as a result of the above accommodation process, the manufacturer of thegas cells irradiates a laser beam 51 onto the solid substances 50arranged on the holes 41 from the +z direction side. With this, thesolid substances 50 are molten and deformed so as to change to sealingmembers 52 which close the small-diameter portions 413 of the holes 41.The solid substances 50 are molten by heating with the laser irradiationso as to be a molten state. If the molten metal drops in thesmall-diameter portions 413, the molten metal is rapidly cooled from thesurrounding while the shape thereof being kept with surface tension ofitself. With this, the molten metal is solidified while keeping theshape thereof. The solidified materials correspond to sealing members52. That is to say, the sealing members 52 close the small-diameterportions 413. With the sealing members 52, the spaces 11 and the airflow path 62 are shielded from one another so that the spaces 11 aresealed. FIG. 11 is a view illustrating a state of the gas cells when thesealing process has been completed. If the laser beam 51 is irradiatedonto each of the solid substances 50, all of the five spaces 11 aresealed by the sealing members 52 as illustrated in FIG. 11.

It is to be noted that although the laser beam 51 is irradiated from the+z direction side to the −z direction side, the irradiation direction isnot limited to the mode and the laser beam 51 may be irradiated from the−z direction side to the +z direction side through the bottom plate 10.

1-6. Air Flow Path Removal Process

After the spaces 11 have been sealed with the sealing members 52, themanufacturer of the gas cells performs an air flow path removal processof removing the air flow path plate 60 from the ceiling plate 40 bygrinding or cutting the air flow path plate 60 with a cutting machine orthe like. FIG. 12 is a view illustrating a state of the gas cells whenthe air flow path removal process has been completed. As illustrated inFIG. 12, since the air flow path plate 60 has been removed, there is noair flow path 62 so that the sealing members 52 are exposed to theoutside. That is to say, the air flow path removal process is an exampleof a removal process of removing a plate having the recess which formsthe air flow path from the cells after the sealing process.

1-7. Reinforcing Process

FIG. 13 is a view illustrating a state of the gas cells in thereinforcing process. The sealing members 52 include a material havingproperty of corroding the alkali metal vapor. Therefore, sealing withthe sealing members 52 for a long period of time may be defective insome case. The reinforcing process is a process of reinforcing thesealing of the spaces 11 with the sealing members 52. In the reinforcingprocess, sealing plates 70 are bonded to the area covering around theholes 41 so as to cover the sealing members 52 exposed to the outside.Each sealing plate 70 may be a transparent member such as a glass or maybe a resin. In other words, it is sufficient that the sealing plates 70are members which are bonded to the ceiling plate 40 by fusion bondingor the like and can make the alkali metal vapor difficult to be flown tothe outside in comparison with the state where the sealing members 52are exposed. That is to say, the reinforcing process is an example of areinforcing process of reinforcing the sealing of the spaces by bondingplate-form members to the cells so as to cover the holes closed by thesolid substances after the removal process.

1-8. Separation Process

FIG. 14 is a view illustrating a state of the gas cells in theseparation process. The separation process is a process of separating astructure formed in the processes by the reinforcing process into aplurality of gas cells 90 each having the space 11 by cutting theseparation wall plates 20 which partition the spaces 11. Themanufacturer of the gas cells cuts the separation wall plates 20 at fourportions as indicated by dashed-two dotted lines in FIG. 14 with acutting tool 80 such as a dicer, a cutter, or a wire-saw. FIG. 15 is aview illustrating a state of gas cells after the separation process hasbeen completed. Each separation wall plate 20 is cut in a direction ofseparating two adjacent spaces 11 from each other with the cutting tool80 so that two wall plates 22 are obtained. With this, the five gascells 90 having the spaces 11 a, 11 b, 11 c, 11 d, 11 e, respectively,are separated from one another and completed. That is to say, theseparation process is an example of a separation process of separatingthe cells from one another by cutting separation walls which partitioninner spaces of the cells. Each gas cell 90 manufactured by the aboveprocesses is an example of a gas cell including a wall for separating aspace which accommodates gas containing atoms which rotate apolarization plane of linearly polarized light in accordance with amagnetic field if the atoms are excited with light from an outer space.In the gas cell, a hole provided on the wall is closed by a molten solidsubstance. Further, the gas cell 90 is an example of a gas cell to whicha plate-like member (sealing plate 70) is bonded to the wall so as tocover the hole closed by the solid substance from the outside.

As described above, with the manufacturing method according to theinvention, spaces which accommodate gas are sealed by melting solidsubstances without using an exhaust pipe. Therefore, with themanufacturing method according to the invention, the spaces can berelatively reduced in size in comparison with a sealing containermanufacturing method of sealing a container by welding an exhaust pipeto the container, heating the exhaust pipe and extending it in a shaftdirection to make an outer diameter thereof smaller, and heating theportion of which outer diameter has been made smaller so as to melt theportion. Further, gas is accommodated in the spaces in a state where thespaces which accommodate the gas are connected to one another with theair flow path. Therefore, concentrations of the gases accommodated inthe cells can be suppressed from being varied.

Further, a welding process and a melting and cutting process for anexhaust pipe are not required to be performed. Therefore, cost and timetaken for manufacturing can be suppressed. In addition, since meltingand cutting by using a burner are not necessary, there is no possibilitythat combustion gas generated from the burner mixes into the gas cells.Moreover, since the exhaust pipe is not welded to the obtained gas cell,the degree of freedom for arrangement of the obtained gas cell is high.Further, spaces which accommodate the gas can be made smaller becausethe exhaust pipe forming a dead space is not provided.

2. Variation

The invention is not limited to the above embodiment and may be executedby varying the embodiment as follows. Further, the following variationsmay be combined.

2-1.

In the above embodiment, alkali metal vapor is accommodated in eachspace 11 in the accommodation process, and each space 11 is sealed witheach sealing member 52 in the sealing process subsequent to theaccommodation process. However, after the alkali metal vapor isaccommodated in the accommodation process, a cooling process of coolingeach space 11 so as to condense the alkali metal vapor may be performedbefore the sealing process. FIG. 16 is a view illustrating a state ofgas cells in the cooling process according to the variation. In thevariation, a cooling unit 33 such as a peltier element is arranged atthe −z direction side of the bottom plate 10 so as to make contact withthe bottom plate 10. After the alkali metal vapor is accommodated ineach space 11 in the accommodation process, the cooling process ofcooling the bottom plate 10 with the cooling unit 33 is performed. Withthis, the accommodated alkali metal vapor is condensed onto wallsurfaces opposed to the spaces 11. That is to say, the cooling processis an example of a cooling process of cooling the cells so as tocondense the gas accommodated in the accommodation process onto wallsopposed to internal spaces.

Then, after the alkali metal vapor has been condensed, theabove-mentioned sealing process is performed. If the alkali metal vaporis condensed in this manner, a concentration of the alkali metal atomsin the gaseous state, which are contained in the spaces 11 and the airflow path 62, is temporarily lowered. Further, if the spaces 11 aresealed in this state, an amount of the alkali metal atoms left in theair flow path 62 which are not used as a magnetic sensor is suppressed.It is to be noted that the cooling unit 33 is not limited to the peltierelement and various cooling devices such as a device which circulates acoolant may be used, for example. The portion cooled by the cooling unit33 is not limited to the bottom plate 10 and it is sufficient that anyof wall surfaces opposed to the spaces 11 are cooled.

Further, in addition to or in place of the cooling process by thecooling unit 33, a heating process of heating the cells and an externalspace of the cells by using a heating unit may be performed. Forexample, the heating unit may make the alkali metal atoms left in theair flow path 62 easy to move to the above wall surfaces opposed to thespaces 11 by heating the air flow path 62 to a temperature higher thanthose of any of the wall surfaces opposed to the spaces 11. That is tosay, it is sufficient that the cooling unit 33 or the heating unitgenerates a temperature gradient on inner walls of the cells such that atemperature is lower as is farther from the holes of the cells. That isto say, the process performed by the cooling unit 33 or the heating unitis an example of a temperature gradient generation process of generatinga temperature gradient on inner walls of the cells such that atemperature is lower as is farther from the holes of the cells.

2-2.

In the above embodiment, one hole 41 is provided on the ceiling plate 40at a position corresponding to each space 11. However, two or more holes41 may be provided at positions corresponding to one space 11. FIG. 17is a view illustrating a state of gas cells in the accommodation processaccording to the variation. As illustrated in FIG. 17, one hole 41 isprovided on the ceiling plate 40 at each of positions corresponding tothe space 11 a and the space 11 e and two holes 41 are provided thereonat each of positions corresponding to the spaces 11 b, 11 c, 11 d.

If two holes 41 are provided for one space 11, for example, when anatmospheric pressure in a space adjacent to one of the two holes 41 ishigher than an atmospheric pressure in a space adjacent to the other ofthe two holes 41, the one hole 41 serves as an inlet of gas for thespace 11 and the other hole 41 serves as an outlet of gas for the space11. That is to say, if two or more holes 41 are provided for one space11, any one of the holes 41 serves as an inlet of gas and other holes 41serve as outlets of gas with a difference of the atmospheric pressuretherearound. Therefore, gas is easy to flow through the spaces 11 incomparison with a case where one hole is provided for one space 11.Accordingly, the alkali metal atoms are easy to be accommodated in thespaces 11 in the accommodation process.

It is to be noted that the spaces 11 for which two or more holes areprovided are not the space 11 a at an end in the −y direction and thespace 11 e at an end in the +y direction but the spaces 11 b, 11 c, 11d. However, the invention is not limited thereto. That is to say, it issufficient that two or more holes are provided for at least one cellamong the plurality of cells.

Further, when two or more holes are provided for one space 11, an airflow path which connects the two or more holes to one another at theoutside of the spaces 11 may be reduced in diameter or closed. FIG. 18is a view illustrating a state of the gas cells in the accommodationprocess according to the variation. As illustrated in FIG. 18, two holes41 are provided for each of the spaces 11 b, 11 c, 11 d. Further, aprotrusion 63 is provided on the air flow path 62 at each of portions onwhich pairs of holes 41 provided on the spaces 11 b, 11 c, 11 d areconnected to one another at the outside of the holes 41.

The air flow path 62 is reduced in diameter with the protrusions 63.Therefore, portions on which the protrusions 63 are provided havepressure loss larger than that of other portions on which theprotrusions 63 are not provided and gas is difficult to flow through theportions. Therefore, airflows as indicated by arrows in FIG. 18 are easyto be generated in the spaces 11 b, 11 c, 11 d. That is to say, an airflow path which connects two or more holes 41 provided for the spaces 11at the outside of the holes 41 is difficult to function as a so-calledbypass if the protrusions 63 are provided. Therefore, circulation andextrusion flow of gas in the spaces 11 are prompted. Accordingly, thealkali metal vapor is easy to be accommodated in the accommodationprocess in the spaces 11 in comparison with a case where theconfiguration is not provided. It is to be noted that the air flow path62 may be closed by the protrusions 63. That is to say, the air flowpath 62 according to the variation is an example of an air flow paththat is reduced in diameter or closed such that gas is difficult to flowthrough portions on which two or more holes 41 provided for one cell areconnected to one another in comparison with other portions.

2-3.

In the above embodiment, the gravity direction is set to the −zdirection. However, the gravity direction in the invention is notlimited thereto and the invention can be applied to an environment inwhich gravity is not applied. Even in this case, it is sufficient thateach member is configured such that the large-diameter portions 411 ofthe holes 41 position the solid substances 50, and if the solidsubstances 50 are molten, the solid substances 50 flow into thesmall-diameter portions 413 to close the holes 41.

Further, in the above embodiment, the holes 41 have the large-diameterportions 411, the steps 412, and the small-diameter portions 413.However, the holes 41 may not have these portions. That is to say, anyconfigurations of the holes 41 and any shapes of the solid substances 50may be employed as long as the solid substances 50 before being moltenare arranged at positions corresponding to the holes 41 and thecorresponding holes 41 are closed if the solid substances 50 are molten.

2-4.

In the above embodiment, a gas containing the alkali metal atoms isaccommodated in the spaces 11 of the gas cells 90. However, another gasmay be accommodated therein. That is to say, it is sufficient that a gascontaining atoms which rotate a polarization plane of linearly polarizedlight in accordance with a magnetic field if the atoms are excited withlight is accommodated in each space 11.

2-5.

In the above embodiment, the manufacturer of the gas cells performs theair flow path removal process of removing the air flow path plate 60from the ceiling plate 40 by grinding or cutting the air flow path plate60 with a cutting machine or the like. However, the air flow pathremoval process may be not necessary if the gas cells 90 can be used ina state where the air flow path 62 is still being bonded to the gascells 90. In this case, a reinforcing process of bonding the sealingplates 70 to portions from which the air flow path is removed is notalso required to be performed.

2-6.

In the above embodiment, the manufacturer of the gas cells performs theseparation process of cutting the separation walls at four portions asindicated by dashed-two dotted lines in FIG. 14 with the cutting tool 80such as a dicer and a cutter. However, the separation process may be notnecessary if the gas cells 90 may be used in a state of not beingseparated from one another.

2-7.

In the above embodiment, the material of each solid substance 50 isgold-based alloy solder such as Au—Sn. However, the material of thesolid substance 50 is not limited thereto. That is to say, it issufficient that each solid substance 50 is a solid substance which ismolten so as to close each hole 41.

2-8.

In the above embodiment, the bottom plate 10, the side wall plates 21,and the separation wall plates 20 are bonded to one another, and then,the front plate and the rear plate are bonded thereto. However, thebonding order is not limited thereto. Further, configurations of the gascells assembled in the assembling process may be such that injectionmolding by using a transparent resin and a mold is employed instead ofbonding the plates.

2-9.

In the above embodiment, the ampule 30 is formed by a material that isbroken if any energy such as impact is applied to an outer skin thereof.However, the ampule 30 may be formed by a material other than the abovematerial. For example, the ampule 30 may be formed by a material whichbreaks after a constant period of time has passed. In this case, if timeis adjusted such that the alkali metal vapor is generated from theampule 30 at a time at which the accommodation process is started, anoperation is not required to be performed on the ampule 30 from theoutside of the cell. A system for breaking the ampule 30 may not dependon the material thereof. For example, a device which applies impact tothe ampule 30 at a predetermined timing may be installed additionally.

Further, the ampule 30 is installed in the space 11 a in the assemblingprocess. However, a member to be installed may not be an ampule as longas the member is a generation source which generates alkali metal vaporin the accommodation process. Further, the generation source whichgenerates the alkali metal vapor may be installed not in any of thespaces 11 but on a portion corresponding to the air flow path 62 as aresult of the air flow path formation process. That is to say, it issufficient that the generation source which generates gas containingatoms which rotate a polarization plane of linearly polarized light inaccordance with a magnetic field if the atoms are excited with light inthe accommodation process is installed in at least one cell or on aportion which becomes the air flow path after the formation process inthe assembling process.

2-10.

The invention can be specified as a manufacturing apparatus formanufacturing the above gas cell 90. FIG. 19 is a view illustrating aconfiguration of the manufacturing apparatus 100 for manufacturing theabove gas cell 90. The manufacturing apparatus 100 includes anassembling unit 101, an arrangement unit 102, an air flow path formationunit 103, an accommodation unit 104, a sealing unit 105, an air flowpath removal unit 106, a reinforcing unit 107, and a separation unit108.

The assembling unit 101 includes a transportation device, a heatingdevice, and a control device. The transportation device transports theabove-described transparent members (bottom plate 10, side wall plates21, separation wall plates 20, front plate, and rear plate) and theampule 30 to respective predetermined positions. The heating deviceheats the transported transparent members so as to fusion-bond thetransparent members to one another. The control device controls thetransported transparent members by a controller including a centralprocessing unit (CPU), a read only memory (ROM), and a random accessmemory (RAM). Under the control by the control device, the transparentmembers are arranged, the ampule 30 is arranged, the transparent membersare fusion-bonded to one another by the heating device so that astructure as illustrated in FIG. 4 is assembled. It is to be noted thatthe assembling unit 101 may be a device which performs injection moldingas described in the above variation.

The arrangement unit 102 includes a transportation device and a controldevice. The transportation device arranges the solid substances 50 onthe holes 41 of the ceiling plate 40. The control device controls thetransportation device. Under the control by the control device, thesolid substances 50 are arranged as illustrated in FIG. 6.

The air flow path formation unit 103 includes a positioning device, aheating device, and a control device. The positioning device positionsthe air flow path plate 60 at a position opposed to the ceiling plate40. The heating device heats the ceiling plate 40 and the air flow pathplate 60 so as to fusion-bond them to one another. The control devicecontrols the positioning device and the heating device. Under thecontrol by the control device, the air flow path 62 is formed asillustrated in FIG. 8.

The accommodation unit 104 includes an irradiation device and a controldevice. The irradiation device irradiates a short-pulse laser beam 31onto the ampule 30 from the outside, for example. The control devicecontrols the irradiation device. Under the control by the controldevice, the ampule 30 is broken and becomes the broken ampule 32 asillustrated in FIG. 9. With this, the alkali metal vapor is accommodatedin each space 11.

The sealing unit 105 includes an irradiation device and a controldevice. The irradiation device irradiates a laser beam 51 onto the solidsubstances 50 arranged on the holes 41. The control device controls theirradiation device. Under the control by the control device, the solidsubstances 50 are molten to change to the sealing members 52 so as toclose the holes 41 as illustrated in FIG. 11.

The air flow path removal unit 106 includes a cutting device and acontrol device. The cutting device cuts the transparent members. Thecontrol device controls the cutting device. Under the control by thecontrol device, the air flow path plate 60 is cut so as to be removedfrom the ceiling plate 40 as illustrated in FIG. 12.

The reinforcing unit 107 includes a transportation device, a heatingdevice, and a control device. The transportation device transports theplurality of sealing plates 70 to positions corresponding to the holes41. The heating device heats the transported sealing plates 70 so as tofusion-bond the transported sealing plates 70 to portions around theholes 41 on the ceiling plate 40. The control device controls thetransportation device and the heating device. Under the control by thecontrol device, the sealing plates 70 are fusion-bonded to the ceilingplate 40 so as to close the holes 41 as illustrated in FIG. 13.

The separation unit 108 includes a cutting device and a control device.The cutting device cuts the separation wall plates 20. The controldevice controls the cutting device. Under the control by the controldevice, the separation wall plates 20 are cut so that the gas cells 90are separated from one another as illustrated in FIG. 15.

What is claimed is:
 1. Apparatus for forming gas cells comprising: atleast a first cell and a second cell; a broken ample disposed in thefirst cell; alkali metal vapor filled in at least the second cell; afirst hole formed on a wall of the first cell and a second hole formedon a wall of the second cell; and wherein the first hole and the secondhole are closed by a molten solid substance.
 2. Apparatus according toclaim 1, further comprising: an air flow path formed on an outer surfaceof the first cell and the second cell; wherein the air flow pathconnects the first hole and the second hole.
 3. Apparatus according toclaim 1, further comprising: a sealing plate covering at least thesecond hole.
 4. Apparatus according to claim 1, wherein: the first andsecond cells are separated by a plate sufficiently thick that it can becut to separate the first and second cells yet provide each cell with aside wall to maintain an enclosure for each cell.